Note: Contributing Writer David Dietz is based in Cairo and doing freelance reporting. For more of his opinions and coverage of Middle East politics, see his blog, TheMidEaster.com, where this story originally appeared.

Last week, a Jerusalem city bus was ripped apart by an explosive device, marking the first time in seven years that Jerusalem has come under such an attack. The explosion, which could be heard throughout Jerusalem, was the first of its kind since 2004 - 2005, when Jerusalem and Tel-Aviv were subjected to a rash of similar bombings.

The bomb, which struck a crowded bus stop and killed 1 person and injured 30 others, may have been a symbolic attack on Bus #74, which carries passengers to Har Homa, one of Israel’s largest contested settlements. Likely in retaliation for the deaths of eight Palestinians killed in Gaza by Israeli air and mortar strikes, the gruesome attack signaled a troubling escalation of violence by both sides.

Although no one or no group has yet claimed responsibility, the Israeli government – through information gathered by the police – has blamed “Palestinian terrorist organizations.”

Shortly after the attack and before embarking on a previously scheduled trip to Russia, Prime Minister Benjamin Netanyahu raised the temperature when he said, “The government, the Israel Defense Forces, and the Israeli public has an iron will to defend the country and its citizens.”

Concerned about possible further violence, President Obama attempted to interject a sense of calm during a press conference stressing, “There is never any possible justification for terrorism. The United States calls on the groups responsible to end these attacks at once and we underscore that Israel, like all nations, has a right to self-defense.” Eager not to appear one-sided, Obama also added, “we also express our deepest condolences for the deaths of Palestinian civilians in Gaza yesterday” before emphasizing the “the importance of calm.”

In his closing remarks, Obama underscored the point by asking “all parties do everything in their power to prevent further violence and civilian casualties.”

Unfortunately, such words may have come too late as earlier that day, fresh rockets rained down on southern Israel and later, Israel’s Defense Minister Ehud Barak threatened retaliation against Hamas if they are found to be linked to the attack. “We will not tolerate the harming of Israeli citizens, not in the south and not in Jerusalem,” said the Defense Minister. “Hamas is responsible for the firing of rockets toward Beersheba today and this responsibility has a price.”

Besides the threat of a retaliatory escalation in violence, the bombing also hampers Palestinian President Mahmoud Abbas’ efforts of Palestinian unification. Mr. Abbas, who was preparing for his first trip to Gaza since 2007, also condemned the bombing in an official statement on the Palestinian news agency website. Hamas and Fatah are both under heavy pressure to reunite, as many see unity between the two as Palestine’s best chance for statehood. Last week’s bombing will almost assuredly delay, if not derail, any chance of the anticipated meeting as everyone awaits Israel’s response.